Importance of characterising the dynamic circulation from altimetry to understand marine ecosystems of Kerguelen

Cedric Cotte (Sorbonne Universités UPMC-CNRS-IRD-MNHN, LOCEAN, France)


Francesco d'Ovidio (Sorbonne Universités UPMC-CNRS-IRD-MNHN, LOCEAN, France); Christophe Guinet (CEBC-CNRS, France); Nolwen Behagle (IRD, UMR Lemar, France); Gildas Roudaut (IRD, UMR Lemar, France); Patrice Brehmer (IRD, UMR Lemar, France); Erwan Josse (IRD, UMR Lemar, France); Yves Cherel (CEBC-CNRS, France)

Event: 2014 Ocean Surface Topography Science Team Meeting

Session: Science Results from Satellite Altimetry: Finer scale ocean processes (mesoscale and coastal)

Presentation type: Type Poster

The Antarctic Circumpolar Current (ACC) is a major physical feature in the Southern Ocean. It structures water masses and it is dominated by an intense turbulence. This dynamic environment is known to influence the low level of trophic webs, i.e. phytoplankton. However the effect of the ACC on higher trophic levels is mostly unknown. The advance in satellite technology, particularly in altimetry, for measuring physical oceanographic features has been essential to understand the marine dynamics and circulation at global scale. These measurements were also the basis of studies conducted at mesoscale (about 100 kms) and submesoscale (1 km to 10 km), often defined by eddies and fronts/filaments. The aim of the ongoing Mycto-3D-Map program is thus to understand how this dynamic circulation influence ecosystems in the Kerguelen pelagic area (southern Indian ocean). In-situ data on mid-trophic levels (mainly fish and zooplankton) were collected from onboard hydroacoustic device (echosounders) together with pelagic trawl in January 2014. Lagrangian diagnostics derived from altimetry were used to describe and characterize quantitatively the transport properties in the region. The relationships between the mesoscale-submesoscale physical drivers and the horizontal-vertical distribution of biological density and diversity suggested an important role of the circulation on marine biota and predator-prey trophic interactions. New insights on physical-biological interactions occuring in the Southern Ocean arise from such integrative sutdies, and altimetry is pivotal in this interdisciplinary approach.
Cedric Cotte
Sorbonne Universités UPMC-CNRS-IRD-MNHN, LOCEAN